This invention relates to methods of treating humans afflicted with psoriasis by treatment with an antipsoriatic amount of tin protoporphyrin (SnPP) or tin mesoporphyrin (SnMP).
Both SnPP and SnMP are known compounds. Their utility in the treatment of hyperbilirubinemia has been described by Drummond and Kappas. The utility of SnPP for this purpose is described in Proc. Nat. Acad. Sci. USA 78 6466-6470 (1981). The use of SnMP is described in commonly owned copending patent application Ser. No.: 715,515 filed Mar. 25, 1985 now U.S. Pat. No. 4,657,902.
Clinically, psoriasis vulgaris is characterized by erythematous, scaling plaques that often begin in the extensor aspects of the body. It may be extremely widespread, with occasional total skin involvement. It is frequently distressing to the patient and occasionally life threatening.
Other clinical types of psoriasis include generalized pustular psoriasis, localized pustular psoriasis of palms and soles, and exfoliative or erythrodermic psoriasis.
Histologically, psoriasis is characterized by acanthosis (thickened epidermis) and parakeratosis (nucleated cells in stratum corneum) and has been described as showing benign hyperplasia. The dermal blood vessels are abnormally tortuous and dilated, and lymphocytic infiltration is frequently seen in the dermis and occasionally in the epidermis.
It is not known whether the available antipsoriatic drugs act to slow cell proliferation primarily or to normalize keratinization. Some of the effective therapies appear to act as antiproliferative agents, and either reduce rates of epidermal KNA synthesis and/or mitosis, or both. For example, topical corticosteroids, anthralin, methotrexate, topical 5-fluorouracil, psoralen plus long-wave ultraviolet light inhibit epidermal DNA synthesis and/or mitotic rate. Retinoids, however, may act primarily partially to correct the abnormal differentiation seen in psoriasis.
Many treatments involving a wide variety of therapeutic agents have been used in attempts to ameliorate psoriasis. These have included the use of topical and systemic steroids; various coal tar preparations, often in association with untraviolet light treatments, trihydroxyanthracene (Dithranol), and methotrexate. More recently, psoralen which is 7H-furo[3,2-g][1] benzopyran-7-one in associated with ultraviolet light has been widely investigated as a method of treatment. The method is known as PUVA.
Despite extensive and strenous efforts no completely satisfactory method of treating human psoriasis has yet been devised.